Boletus fechtneri
Silver Boletus (Boletus fechtneri )
The silver or Summer Boletus (Boletus fechtneri ) is a species of fungus in the family Dickröhrlingsverwandten.
- 4.1 hazard
Features
Macroscopic characteristics
The hat of silver Röhrlings is hemispherical to cushion -shaped and reaches a diameter of 6-18, sometimes 25 cm; at the age he can flatten slightly. In young fruit bodies of the hat is gray-white to silvery gray or nearly pure white and noticeably fibrous- felted. Later, he is of gray brownish color and smooth down ( glabrous ); rarely it can also be tinted pink brownish. In case of contact interface runs on brownish to reddish. The tubes are colored lemon to golden yellow; in contact they get a blue color. The pores have the same tint as the tubes, but may be tinged with reddish brown; they change color after exposure also blue.
The stem of the mushroom is between 5-12 cm long and 2-4 cm thick. When young it has a bulbous shape, later he is cylindrical to clavate. The base often is tapered. The surface is pale yellow to cream- colored and covered with a fine yellow network. At the bottom of a narrow reddish zone is present.
The meat ( Trama ) is bright yellow. It turns sky blue and reddish in the lower stem portion in case of injury in the hat. In between, a pale blue or light grünlichbaue tint appears. This color distribution seems so only in silver Boletus. After a few hours the color faded to a dull yellow. The flavor of the meat is mild.
Microscopic characteristics
The spores of silver Röhrlings are fusiform in shape and measure 30-40 x 9-13 microns. The carrying them basidia are 30-40 × 9-13 microns in size. The cystidia have a bulbous to narrowly fusiform or bottle- like shape and a size of 10-15 × 4-6 microns. The Hutdeckschicht consists of interwoven hyphae, extending the ends partially, but to lie down later. They are 3-9 microns thick and have cylindrical, club-shaped end cells rarely.
Artabgrenzung
The silver - Röhrling be confused with other grauhütigen, gelbporigen boletes. These include the Bitter Boletus radicans (B. radicans ) and the Schönfuß Boletus (B. calopus ), both of which have a bitter taste. The latter also usually has a clear red stem. There is also similarity with the Pale or Blasshütigen Boletus ( Hemileccinum impolitum ), which already has significant young brown tones in the hat, does not have a handle network and does not discolor in injury. Blasshütige forms of the king - Röhrlings (B. regius ) may also be similar. Their meat also does not discolor in injury.
Ecology and phenology
The silver Boletus is a quite rare fungus that is lime-and heat -loving. It is mainly found in deciduous forests with beeches and preference is thermally favored tree stands. It also occurs in oak-hornbeam forests.
Like other Dickröhrlingsverwandte is the silver Röhrling to meet together with other species of the genus Boletus. These include primarily the blue end Königsröhrling (B. pseudoregius ), the Königsröhrling (B. regius ) and the False Satansröhrling (B. legaliae ) and also the Schwarzhütige cep (B. aereus ), the Anhängselröhrling (B. appendiculatus ) and the Glattstielige bolete (B. queletii ) and sometimes the Satansröhrling (B. satanas ). All of these species are also quite rare.
The fruiting bodies appear between July and late September. Sometimes early October still copies can be found.
Distribution and threat
The silver - Röhrling is meridionally to temperat common and found throughout Europe in the book areas. However, it is rare everywhere. To the north, the distribution extends approximately central Sweden and England. In Germany, the mushroom in the south is scattered to rare; in the north it is particularly rare.
Endangering
The silver Boletus is a now rare fungus in its preference for basic soils, for the numerous locations a decrease was observed. Gminder et al. suggest that the mushroom is critically endangered ( RL 1).
Importance
The mushroom is edible, but should be spared because of its rarity.